The invention relates to improvements in methods of and in apparatus for draping successive objects of a series of objects into a wrapping material, especially into webs of wrapping material. More particularly, the invention relates to improvements in methods of and in apparatus for draping the objects (especially substantially block-shaped objects, such as stacks of overlapping paper sheets) into pairs of deformable webs of wrapping material.
It is already known to drape successive objects of a row of block-shaped or like objects into a pair of webs one of which is supplied from below and the other of which is supplied from above. The marginal portions of the webs are caused to overlie each other to be thereupon welded or otherwise sealingly secured to each other. It is also known to thereupon provide the resulting tubular body with transversely extending seams, so as to segregate successive objects from each other, and to sever the overlapping webs along such seams so that the objects become physically separated from each other. If the webs are made of shrinkable plastic or like material, the separated draped objects are introduced into a heating chamber wherein the webs shrink to form envelopes which closely conform to the outlines of the respective objects.
German Offenlegungsschrift No. 25 12 005 discloses an apparatus wherein two elongated webs are draped around a series of successive objects in such a way that each web forms a substantially U-shaped or trough-shaped body and the two bodies are mirror symmetrical to each other. If the objects are block-shaped commodities, the marginal portions of the two U-shaped bodies abut each other at a level substantially midway between the upper sides and the undersides of the objects. The width of the two webs suffices to ensure that the U-shaped bodies are provided with laterally outwardly extending marginal portions which are thereupon welded to each other so that the two bodies together form an elongated tubular envelope containing a series of spaced-apart objects.
A modified draping apparatus is disclosed in German Offenlegungsschrift No. 25 19 144 wherein a single web is converted into a tube with two flaps formed by the marginal portions of the web. The flaps overlap and are thereupon bonded to each other. The overlapping flaps are adjacent one side of the row of objects which are confined in the tube.
Each of the aforedescribed apparatus exhibits a number of drawbacks. Thus, if the marginal portions of a single web or of two webs overlap each other at a level between the upper sides and the undersides of the respective objects, such marginal portions can interfere with the introduction of discrete wrapped and sealed objects into boxes or other types of containers. Moreover, the marginal portions which are disposed at such levels detract from the appearance of the draped and sealed objects, and they cannot be readily reached to be removed in order to afford access to the confined objects.